Improvements in or relating to refrigerated display appliances

ABSTRACT

A ducted shelf assembly for a refrigerated display appliance comprises separate upper and lower supports, each being separately engageable with support formations to hold the shelf structure at a desired height against a wall of the display appliance. At least one duct element is separate from and disposed between the lower support and the upper support, the duct element then being supported by the lower support and retained by the upper support.

This invention relates to refrigerated display appliances, exemplified in this specification by refrigerated multi-deck display cases or cabinets that are used in retail premises for cold-storage, display and retailing of chilled or frozen food and drink products.

The invention is not limited to retail food and drink cabinets. For example, the principles of the invention could be used to display other items that require cold storage, such as medicines or scientific items that may be prone to degradation. However, the principles of the invention are particularly advantageous for retail use.

It is well known to fit sliding or hinged glass doors to the front of a refrigerated display cabinet. In theory, but unfortunately not in practice, cold air is held behind the doors, preventing ‘cold aisle syndrome’ caused by cold air spilling from the open front of the cabinet into an aisle of such cabinets in retail premises. Aside from causing discomfort to shoppers, cold aisle syndrome wastes energy in keeping the cabinets cold and the retail premises warm.

Equipping a refrigerated display cabinet with doors has key disadvantages in a retail environment. Doors put a barrier between the shopper and the displayed items, which can reduce sales very significantly. Doors also create a barrier, and additional work, for staff tasked with restocking, cleaning and maintaining the cabinets, which adds significantly to retail overheads. Also, wider aisles may be needed to allow shoppers to open doors and to manage trolleys, which reduces the sales return per square metre of retail space. Additionally, heat may need to be applied to the doors to reduce fogging and misting following door opening, which increases energy consumption.

Despite incurring these significant disadvantages, doors do not work effectively to retain cold air for the simple reason that shoppers and staff in busy retail premises will open the doors frequently and sometimes for extended periods. Whenever the doors are open, cold dense air will spill out. The cold air lost from inside the cabinet will inevitably be replaced by ambient air. Consequently, in real conditions, the addition of doors to a cabinet does not significantly improve energy consumption, temperature control and ingress of ambient air.

Ingress of ambient air is undesirable during the operation of any refrigerated display appliance. The heat of incoming ambient air increases cooling duty and hence the energy consumption of the appliance. The moisture that the air carries causes condensation, which may also lead to icing. Condensation is unsightly, offputting and unpleasant for shoppers, may threaten reliable operation of the appliance and promotes microbial activity which, like all life, requires the presence of water. Also, the incoming ambient air will itself contain microbes, dust and other undesirable contaminants.

Specifically, when ambient air that is warm and moist enters the cabinet, it warms items stored within the cabinet and deposits moisture upon them as condensation. Warmer temperatures and higher moisture levels promote microbial activity, which reduces shelf-life, causes off-odours, promotes fungal growth and can cause food poisoning.

Shoppers like open-fronted multi-deck display cabinets without doors, as such cabinets provide unhindered access so that the items on display may be easily viewed, accessed and removed for closer inspection and purchase. Retailers also like such cabinets because they allow a wide range of products to be displayed clearly to and accessed easily by shoppers, with reduced maintenance overheads and better utilisation of retail floor space.

Typically, open-fronted refrigerated display cabinets employ a large downwardly-projected refrigerated air curtain extending between discharge and return air terminals from top to bottom over an access opening defined by the open front face of the cabinet. The purposes of the air curtain are twofold: to seal the access opening in an effort to prevent cold air spilling out from the product display space behind; and to remove heat from the product display space that is gained radiantly through the access opening and via infiltration of ambient air into the product display space.

A conventional air curtain requires high velocity to remain stable enough to seal the access opening of the cabinet. Unfortunately, however, high velocity increases the rate of entrainment of ambient air into the air curtain. Entrainment of ambient air drives infiltration of the ambient air into the product display space and contributes to spillage of cold air from the appliance. Also, a high-velocity stream of cold air is unpleasant for a shopper to reach through to access the product display space behind the air curtain.

Additional cooling air is typically supplied via a perforated back panel behind the product display space of the cabinet. That additional cooling air is bled from ducts supplying the air curtain to provide more cooling at each level within that space and to support the air curtain. This allows the air curtain velocity to be reduced and so reduces the entrainment rate of ambient air. However, even with measures such as back panel flow, conventional cabinets can suffer from ambient air entrainment rates as high as 80% in real conditions, causing excessive energy consumption and uncomfortably cold aisles.

Back panel flow has the disadvantage that the coldest air blows over the coldest items at the back of the shelves, which are subject to the lowest heat gain because they are furthest from the access opening. This undesirably increases the spread of temperature across items stored in the product display space. In this respect, it is vital that tight temperature control is maintained throughout the product display space of the cabinet. Regions of a cabinet warmer than the desired temperature will suffer from faster food degradation. Conversely, regions of a cabinet colder than the desired temperature may cycle above and below the freezing point, again promoting faster food degradation.

The levels within a refrigerated display cabinet are typically defined by one or more shelves, which may for example comprise solid or perforated panels or open baskets. Shelves partition the interior of the cabinet into a stack of two or more smaller product display spaces. Shelves and their associated product display spaces may also be partitioned into side-by-side columns. Each product display space is accessible through a respective open frontal access opening. Specifically, each shelf defines an upper access opening above the shelf and a lower access opening below the shelf affording access to refrigerated items in respective product display spaces in a cold-storage volume above and below the shelf.

Several proposals have been made to duct air through shelves of refrigerated display cabinet, to and/or from outlets and/or inlets forwardly-positioned on the shelf, to generate or to support air curtains. The aim is to help an air curtain to seal the open front of the cabinet more effectively, improving temperature control and lessening infiltration of ambient air.

In the Applicant's previous patent application published as WO 2011/121284, at least one forwardly-positioned discharge outlet communicates with a supply duct to project cold air as an air curtain across an access opening. At least one forwardly-positioned return inlet communicates with a return duct to receive air from the air curtain. Where the air curtain flows conventionally downwardly from top to bottom, the discharge outlet projects cold air as an air curtain across the lower access opening below the shelf and the return inlet receives air from another air curtain discharged above the shelf across the upper access opening above the shelf.

It is possible, albeit unconventional, for an air curtain to flow upwardly across an access opening from bottom to top. In that case, the discharge outlet projects cold air as an air curtain across the upper access opening and the return inlet receives air from another air curtain discharged below the shelf across the lower access opening. The present invention also encompasses this possibility.

WO 2011/121284 teaches a ducted shelf whose frontal structure comprises a downwardly-facing discharge opening or outlet and an upwardly-facing return opening or inlet. Each of those openings extends parallel to the shelf front and communicates with a respective duct stacked one above the other in the shelf or lying one beside the other in the shelf to supply air to the outlet and to receive air from the inlet.

The front of a ducted shelf comprises a downwardly-facing discharge opening and an upwardly-facing return opening, each communicating with a respective duct stacked one above the other in the shelf. Airflow management features including baffles, risers and flow straighteners are associated with these openings to ensure good air curtain performance.

By their nature, ducted shelves comprise more components than non-ducted shelves and therefore tend to be considerably bulkier and heavier. This presents challenges during installation, adjustment and maintenance if large and heavy assemblies must be lifted and manoeuvred. For example, health and safety guidelines on manual handling dictate that male workers may lift no more than 20 kg at or above elbow height, even close to the body. This decreases to 5 kg when the arms are extended at or above shoulder height. These limits are even lower for female workers.

The requirement for additional workers or lifting equipment to handle heavier shelves increases the cost of operation and makes installation, adjustment and maintenance operations lengthy and complicated. Consequently, there is a disincentive to adjust the height or position of ducted shelves or to maintain refrigerated displays properly, as shelves may need to be removed for cleaning or for the servicing or replacement of other parts.

There is a need for ducted shelves that are easy to install, adjust and maintain, while being inexpensive, effective and yet simple to assemble and disassemble.

It is against this background that the present invention has been devised.

From one aspect, the invention resides in a ducted shelf assembly comprising:

-   -   at least one support that is engageable with support formations         to hold the shelf assembly at a desired height against a wall of         a display appliance; and     -   at least one duct element that is separate from and positionable         upon the support, the duct element then being supported by the         support.

The assembly may further comprise a top shelf component, which may comprise a top plate of the shelf that overlies the, or each, duct element.

The top shelf component may comprise a shelf front strip that is insulated, heated or of low thermal conductivity and that is arranged to cover a front edge of the, or each, duct element.

The assembly preferably comprises a supply duct element and a return duct element.

Advantageously, the assembly comprises separate upper and lower supports, each being separately engageable with support formations to hold the shelf assembly at a desired height against a wall of a display appliance, wherein the duct element is separate from and positionable between the lower support and the upper support, the duct element then being supported by the lower support and retained by the upper support.

Preferably, the lower support and the upper support are separately and successively engageable with the support formations upon assembly of the structure against the wall. Also, the supply duct element and the return duct element are preferably in layered face-to-face relation and are held together by upper and lower supports.

Conveniently, upper supports positionable above the duct element and/or lower supports positionable below the duct element comprise sealing elements arranged to seal against the wall of the display appliance. The, or each, sealing element is suitably arranged to seal against the, or each, duct element, and preferably has a wall that extends vertically to an extent that enables sealing against the wall of the display appliance to be maintained if a support is engaged with support formations at a different level on the wall.

The invention extends to a ducted-shelf air curtain display unit, comprising at least one ducted shelf assembly of the invention. The unit suitably comprises an open-fronted cabinet having a display space bounded by an upright wall, that wall being disposed between the display space and at least one riser duct for the supply and/or return of air; wherein:

-   -   the ducted shelf is selectively locatable in the display space         at different heights relative to the upright wall and         communicates with the riser duct by engagement of a connector of         the shelf via at least one port in the upright wall;     -   the port is deeper vertically than the connector of the shelf         such that the shelf can be relocated vertically with the         connector remaining in communication with the riser duct via the         port after relocation; and     -   a sealing element is relocatable with the shelf to extend         between the shelf and the upright wall, the sealing element         overlapping an edge of the port to close off a portion of the         port not closed by the connector.

The unit of the invention suitably comprises an upper sealing element extending above the shelf to above an upper edge of the port and a lower sealing element extending below the shelf to below a lower edge of the port. Elegantly, the unit may be arranged such that engagement of a support with the upright wall presses the sealing element against the upright wall.

The inventive concept extends to a method of assembling a ducted shelf in a display appliance, comprising:

-   -   attaching a first support to an upright wall that bounds a         display space of the appliance; and     -   placing at least one duct element onto the first support         attached to the wall.

The method of the invention preferably further comprises attaching a second support to the upright wall to retain the, or each, duct element on the first support. Supply and return duct elements may be stacked on the first support before attaching the second support to the upright wall.

Preferably, the duct element is coupled to a riser duct of the appliance via a port in the upright wall.

Seals may be effected between the first support and the upright wall and between the first support and the or each duct element. Seals may also be effected between the second support and the or each duct element, and between the second support and the upright wall. Elegantly, the seals may be effected simply by assembling together a support and the duct element on the upright wall.

In order that the invention may be more readily understood, reference will now be made by way of example to the accompanying drawings, in which:

FIG. 1 is a sectional side view of a refrigerated display appliance, taken on line I-I of FIG. 2;

FIG. 2 is a sectional top view of the appliance of FIG. 1, taken on line II-II of FIG. 1;

FIG. 3 a is an exploded side view of a supply duct component and a return duct component of a ducted shelf of the appliance;

FIG. 3 b is a side view of the supply duct component and the return duct component assembled together;

FIG. 4 a is an exploded top view of the supply duct component and the return duct component;

FIG. 4 b is a top view of the supply duct component and the return duct component assembled together;

FIG. 5 is an enlarged detail view of how the duct components of the shelf couple with riser ducts of the appliance shown in FIGS. 1 and 2;

FIG. 6 is an enlarged detail view corresponding to FIG. 5 and showing how the shelf is supported from keybars of the appliance shown in FIGS. 1 and 2;

FIGS. 7 a to 7 d are sectional side views of a refrigerated display appliance in accordance with the invention, showing various shelf configurations enabled by the invention;

FIGS. 8 to 12 are a series of enlarged detail side views showing the steps involved in assembling a ducted shelf of the invention;

FIG. 13 is an enlarged detail side view showing how the ducted shelf of the invention may be adjusted for height while remaining sealed to riser ducts of the appliance; and

FIG. 14 is a perspective view of a variant of a lower support.

Referring firstly to FIG. 1, this shows a refrigerated integrated multi-cellular display appliance 10. The appliance 10 has a bottom-mounted evaporator 12 fed with air by supply fans 14, although other arrangements are possible for the production and circulation of cold air. Here, cold air from the evaporator 12 is supplied to a plurality of airflow-managed cells 16A, 16B, 16C that are stacked in a vertical array or column and are all disposed within a single insulated cabinet 18. In this example, there are three cells in the stack, namely a top cell 16A, an inner cell 16B and a bottom cell 16C.

The cells 16A, 16B, 16C are separated here by two ducted shelves 20 constructed in accordance with the invention. The cells 16A, 16B, 16C can be of different heights and may be arranged to store items at different temperatures to reflect storage requirements for various items. The shelves 20 could be fixed but are height-adjustable in this example, as shown by the dashed lines in FIG. 1, so that the relative heights of the cells 16A, 16B, 16C can be adapted to suit different retail requirements.

The ducted shelves 20 each comprise a sandwich of a supply duct 22 and a return duct 24. The shelves 20 subdivide the internal volume of the cabinet 18 into a plurality of product display spaces stacked one atop another, each in its own airflow-managed cell 16A, 16B, 16C. Each shelf 20 defines the top wall of a lower cell in the stack and the bottom wall of an adjacent upper cell in the stack.

The top wall of the top cell 16A is defined by an additional supply duct 22 above a top inner panel of the cabinet 18. Similarly, the bottom wall of the bottom cell 16C is defined by an additional return duct 24 beneath a bottom inner panel of the cabinet 18 that also serves as an additional shelf for the display of refrigerated items. Advantageously, the additional supply duct 22 and the additional return duct 24 may be identical to those used in the shelves 20.

At their back and side edges, the ducted shelves 20 lie closely against the back inner panel 26 and the side walls 28 of the cabinet 18, to discourage airflow around those edges of the shelves 20. Seals may be provided along those edges of the shelves 20 if required.

FIG. 1 also shows optional non-ducted intermediate shelves 30, one at an intermediate level in each cell 16A, 16B, 16C and set back from the front of the ducted shelves 20, to facilitate display of different types of food products and to make best use of the available space. One or more of the intermediate shelves 30 may be perforated or slotted to improve air movement in the cells 16A, 16B, 16C. The intermediate shelves 30 need not seal against the back inner panel 26 or the side walls 28 of the cabinet 18.

Each cell 16A, 16B, 16C is generally in the form of a hollow cuboid or box enclosing a correspondingly-shaped product display space. Front access openings 32 give unhindered reach-in access to any items in the product display spaces defined by the cells 16A, 16B, 16C.

In use, each access opening 32 is sealed by a generally-vertical air curtain 34 that flows downwardly in front of the associated cell 16A, 16B, 16C. The air curtain 34 extends between a downwardly-facing discharge air grille (DAG) or discharge terminal 36 and an upwardly-facing return air grille (RAG) or return terminal 38. Cooled air is supplied through a supply duct 22 to the DAG 36, which projects the air curtain 34, and is returned through a return duct 24 via the RAG 38, which receives air from the air curtain 34. The air received from the air curtain 34 will inevitably include some entrained ambient air, from which heat and moisture must be removed during recirculation within the appliance 10, although the arrangement illustrated will greatly reduce the rate of entrainment in comparison with standard designs.

With reference now also to FIG. 2 of the drawings, the supply ducts 22 and the return ducts 24 that communicate at the front with the DAGs 36 and RAGs 38 respectively communicate at the rear with respective riser ducts 40, 42, namely a supply riser duct 40 and a return riser duct 42. The riser ducts 40, 42 extend upwardly between the back inner panel 26 and the adjacent insulated rear wall of the cabinet 18.

In the example shown in FIG. 2, one supply riser duct 40 is disposed between two return riser ducts 42. FIG. 2 also shows ducted shelves 20 and riser ducts 40, 42 of two columns of cells 16 disposed side-by-side in the common insulated cabinet 18, divided here by a vertical partition 44 that is suitably of transparent material, such as perspex or tempered glass, for ease of viewing.

At its rear edge, the partition 44 lies closely against, and is preferably sealed to, the back inner panel 26. The partition 44 extends from the back inner panel 26 substantially the full depth of the shelves 20 from front to rear. Preferably, as shown, the partition 44 extends slightly forward of the front edges of the shelves 20. The partition 44 prevent air flows from spilling from one column to the next and possibly disrupting the air curtain dynamics of adjacent cells.

The front edge regions of the partition 44 and the shelves 20 may be insulated and/or heated to fight condensation. It is also possible for the front edge regions of the partition 44 and the shelves 20 to be of a low-conductivity material and/or to have a high-emissivity finish.

If shelves 20 of neighbouring columns are aligned, the partition 44 may be removed to increase the effective display area.

Another feature shown in FIG. 2 is that each column has pair of keybars 46 that extend vertically on the outer sides of the return riser ducts 42. The keybars 46 support the weight of the shelves 20 and provide a vertical array of slots into which spigots at the back of a shelf 20 can locate at any suitable height.

In use of the appliance 10, cold air is ducted from the evaporator 12 to each cell 16A, 16B, 16C and warmer return air is returned from each cell 16A, 16B, 16C to the coil 14 for cooling, drying, optional filtering and recirculation.

Air is blown through the evaporator 12 by the fans 14 and then propelled up the central supply riser duct 40. From there, the air enters the supply ducts 22 in the ducted shelves 20 and at the top of the cabinet 18 to be projected as a stack of air curtains 34 through the DAGs 36, one per cell 16A, 16B, 16C. The return air from the air curtains 34 is returned via the RAGs 38 and the return ducts 24 in the shelves 20 and at the bottom of the cabinet 18, to enter the return riser ducts 42 on each side of the central supply riser duct 40. The return air flows downwardly in those return riser ducts 42 under the suction of the fans 14 to enter the evaporator 12 again.

The requirement for airflow to the ducted shelves 20 requires ports 48 in the back inner panel 26 leading to the supply riser duct 40 and the return riser ducts 42. Various port arrangements are disclosed in WO 2011/121285 and so need no further elaboration here. For now, it is sufficient to note that those ports 48 are spaced in vertical arrays aligned with the parallel vertically-extending supply riser duct 40 and the return riser ducts 42, to allow for the shelves 20 to be removed and optionally relocated at different heights. Advantageously, those ports 48 are open only when a shelf 20 is coupled with them to reduce unwanted spillage of cold air into the cabinet 18. Again, WO 2011/121285 discloses ways in which the ports 48 could be closed off when not in use; other arrangements are described in parallel patent applications filed by the Applicant.

Referring next to FIGS. 3 a, 3 b, 4 a and 4 b, these show how separate supply and return duct components 50, 52 respectively are assembled to form a ducted shelf 20 shown in FIGS. 1 and 2. The supply and return duct components 50, 52 are hollow plate-like structures that are laid together in face-to-face relation as part of a ducted shelf 20.

The supply and return duct components 50, 52 have supply and return connectors 54, 56 respectively on their rear edges for connection to respective riser ducts 40, 42 of the appliance 10 shown in FIGS. 1 and 2. Specifically, the connectors 54, 56 are rearwardly-projecting vertically-enlarged extensions of the duct components 50, 52. The connectors 54, 56 employ inclined or curved branch connections to promote even airflow and to minimise static pressure losses. Blade connections 58 at the rear of the connectors 54, 56 facilitate a plug-in arrangement between the connectors 54, 56 and the riser ducts 40, 42 as will be described below in relation to FIG. 5.

The extensions of the respective duct components 50, 52 defining the connectors 54, 56 are offset laterally so as to lie side-by-side and at the same general horizontal level. Specifically, the supply connector 54 is nested between the return connectors 56 when the duct components 50, 52 are assembled together in face-to-face relation as shown in FIGS. 3 b and 4 b.

Inclined or curved transition sections between the duct components 50, 52 and the connectors 54, 56 promote even airflow and minimise static pressure losses as air flows through a throat 60 of reduced duct cross-sectional area. This throat 60 creates a relatively high static pressure, which is desirable to balance airflows between shelves. High-velocity contractions defined by the throats 60 and the lateral offset of the connectors 54, 56 reduce duct sizes and help to make airflow more uniform.

FIG. 5 shows how the blade connections 58 at the rear of the connectors 54, 56 plug in to the riser ducts 40, 42 to couple the riser ducts 40, 42 to the supply and return ducts 22, 24 of a ducted shelf 20. The blade connections 58 have resilience that helps them to seal against the side walls 62 of the riser ducts 40, 42 as the blade connections 58 slide into place.

FIG. 5 also shows one of the pair of keybars 46 that extend vertically on the outer sides of the return riser ducts 42 to support the weight of the shelves 20. That keybar 46 is also shown in FIG. 6, which corresponds to FIG. 5 but additionally shows a spigot 64 projecting rearwardly from the shelf 20 and engaged within a slot in the keybar 46. Preferably the keybars 46 provide a vertical array of slots into which spigots 64 of a shelf 20 can locate at any suitable height, to allow the heights of the shelves 20 to be adjusted as required.

Symmetry, balance and airtightness are important aspects of the airflow-managed cells 16A, 16B, 16C used in the invention. Symmetry arises to a considerable extent from the advantageous modularity of the design. In relation to balance, testing has shown that static pressure losses in the vertical riser ducts 40, 42 are insignificant in comparison with the static pressure losses in the ducted shelves 20 and in the throats 60 leading to or within the shelves 20. Consequently, the relative positions of different shelves 20 along the riser ducts 40, 42 will have little bearing on the system balance. This means that air will flow substantially equally to and from each shelf 20 regardless of its vertical position along the riser ducts 40, 42.

Turning now to FIGS. 7 a to 7 d, ducted shelves 20 may be moved from the mid position by plus or minus 50 mm in these examples. This enables various shelf configurations, some of which are illustrated here.

Specifically, FIG. 7 a shows a total of six shelves comprising an upper ducted shelf 20 and a lower ducted shelf 20, each shown here at mid positions, plus three intermediate shelves 30, one per cell 16A, 16B, 16C, plus a bottom shelf 66 defined by the bottom inner panel of the cabinet 18.

In FIG. 7 b, there are four shelves comprising an upper ducted shelf 20 in a raised position and a lower ducted shelf 20 in a lowered position to maximise the depth of the inner cell 16B, plus one intermediate shelf 30 in that inner cell 16B, plus the bottom shelf 66. Thus, the top cell 16A and the bottom cell 16C do not contain intermediate shelves 30 in this example.

FIG. 7 c shows five shelves, comprising the bottom shelf 66 plus an upper ducted shelf 20 in a lowered position and a lower ducted shelf 20 in a raised position. This minimises the depth of the inner cell 16B and maximises the depth of the top cell 16A and the bottom cell 16C. In this example, the top cell 16A and the bottom cell 16C contain intermediate shelves 30 but the inner cell 16B does not.

Like FIG. 7 a, FIG. 7 d shows a total of six shelves, namely an upper ducted shelf 20 and a lower ducted shelf 20, plus three intermediate shelves 30, one per cell 16A, 16B, 16C, plus a bottom shelf 66. In this example, however, the upper ducted shelf 20 and the lower ducted shelf 20 are each shown in raised positions to maximise the depth of the bottom cell 16C.

FIG. 8 shows a lower support 68 being attached in front of the back inner panel 26 that conceals the riser ducts 40, 42. The lower support 68 comprises side brackets with an inverted L-shape in side view, comprising a horizontal arm 70 for supporting other components of a ducted shelf 20 and a vertical leg 72 that fixes the lower support 68 to the keybars 46 shown in FIGS. 5 and 6. For this purpose, the leg 72 has a vertical array of rearwardly-projecting downwardly-opening hook-type spades serving as spigots 64 to fit into slots in the keybars 46.

The lower support 68 comprises two side brackets, one to each side of a shelf 20, connected by an upright resilient bottom seal plate 74 to form a single fabricated item that can be hooked into the keybars 46 via the spigots 64. The bottom seal plate 74 has a vertical lower portion 76 that is integral with an upper portion 78, which is inclined forwardly and upwardly.

FIG. 8 shows a port 80 provided in the back inner panel 26 that leads to the riser ducts 40, 42. When the lower supports 68 are connected to the keybars 46, the bottom seal plate 74 overlaps the bottom edge of the port 80. In this way, the lower portion 76 of the bottom seal plate 74 seals against the back inner panel 26 immediately beneath the port 80.

Next, FIG. 9 shows the supply duct component 50 being placed onto the arms 70 of the lower supports 68. The supply connector 54 at the rear of the supply duct component 50 is coupled to the riser supply duct 40 via the blade connections 58 at the rear of the connector 54 as shown in FIGS. 5 and 6. The supply connector 54 has a lower face 82 that is inclined upwardly and forwardly and seals against the similarly-inclined upper portion 78 of the seal plate 74.

FIG. 10 shows the next step in the assembly process, namely the addition of the return duct component 52 being placed on top of the supply duct component 50. The return connector 56 at the rear of the return duct component 52 lies beside the supply connector of the supply duct component, and is similarly coupled to the riser supply duct 42 via the blade connections 58 at the rear of the connector 56. The return connector 56 also has a lower face 84 that is inclined upwardly and forwardly and also seals against the upper portion 78 of the seal plate 74.

FIGS. 11 and 12 show the addition of the final component of the ducted shelf 20, namely an upper support 86. The upper support 86 comprises two side brackets, each with an L-shape in side view, one to each side of the shelf 20. Each bracket comprises a horizontal arm 88 supporting a horizontal top tray 90 that extends between the upper supports 86 and covers the entire shelf 20, and an upright member 92 that fixes the upper support 86 to the keybars 46 shown in FIGS. 5 and 6. For this purpose, the upright member 92 has a vertical array of rearwardly-projecting upwardly-opening cam-type spades serving as spigots 64 to fit into slots in the keybars 46.

The side brackets of the upper support 86 are also connected by an upright resilient top seal plate 94 to form a single fabricated item that can be hooked into the keybars 46 via the spigots 64. When the upper support 86 is connected to the keybars 46, the top seal plate 94 overlaps the top edge of the port 80. In this way, the top seal plate 94 seals against the back inner panel 26 immediately above the port 80.

The tray 90 has a transparent front 96, suitably of perspex, and supports a front finisher 98 that is shaped to fit around the front edges of the return duct component 52 and the supply duct component 50 beneath. The finisher 98 is suitably insulated, heated or of low thermal conductivity so as to combat condensation.

The rear of the tray 90 is also seen from above in FIG. 6 closing a gap in front of the keybar 46. Flexible sides of the tray 90 help to seal air inside a cell 16A, 16B, 16C that is partially defined by the shelf 20.

FIG. 13 shows how the shelf 20 may be adjusted vertically by moving the spigots 64 into different levels of slots in the keybars 46. Here, the upper support 86 has not yet been fitted but the lower support 68 is in place, together with the supply duct component 50 and the return duct component 52. The shelf 20 is shown here adjusted to a raised position with respect to the back inner panel 26. It will be apparent that the overlap between the bottom seal plate 74 and the back inner panel 26 beneath the port 80 has been reduced but that a seal has been maintained between the bottom seal plate 74 and the back inner panel 26. When the upper support 86 is fitted, there will be an increased overlap between the top seal plate 94 and the back inner panel 26 above the port 80. Again, therefore, a seal will be maintained between the top seal plate 94 and the back inner panel 26 above the port 80.

The overlap between the top seal plate 94 and the back inner panel 26 above the port 80 is sufficient to allow the shelf 20 to be adjusted into a lowered position while maintaining sealing between the top seal plate 94 and the back inner panel 26 above the port 80.

Finally, FIG. 14 shows a variant 100 of the lower support 68, having cross-members 102 extending between the arms 70 and legs 72 of the side brackets 102. This view omits the bottom seal plate for clarity. Typically the design loading for supermarket shelves is in the order of 250 kg/m² to take the weight of bottles, cartons and other heavy items that may be densely packed on them. Consequently, the cross-members 102 provide structural integrity to meet the demands placed on shelves in a supermarket environment.

The principal components of the shelf 20 are suitably made of light-gauge materials of minimum thickness, utilising bending and folding to achieve strength, rigidity, and straightness. Whilst painted mild steel could be used for most fabricated parts, aluminium could be used for adjustable or removable shelves to reduce their weight and so to make it easier to handle them manually.

By virtue of the invention, a potentially bulky and heavy ducted shelf is broken down into easily-handled elements that can, in effect, be hung sequentially at a desired height and location on a wall of the display appliance. Placing the lower support creates a platform for the subsequently-added duct elements. This eases the installation operation, reduces the risk of injury to workers or damage to equipment and preferably avoids the need for additional manpower or lifting apparatus.

The advantages of the invention are seen not only during installation but also during adjustment of the position or height of a shelf and during maintenance, strip-down and removal. Disassembling the shelf is a simple reverse process that enables easy access to and replacement of components. Disassembly also divides the weight of the shelf into easily-handled components that can be reassembled quickly at a desired alternative height or position.

Many variations are possible within the inventive concept. For instance, in other examples having more than three cells in the stack, there will be more than one inner cell and more than two ducted shelves; conversely where there are only two cells in the stack, there will be no inner cell and only one ducted shelf.

One or both of the side walls of the cabinet could be transparent to enhance visibility of the items displayed in the product display spaces, in which case the side walls are suitably of tempered glass and double- or triple-glazed to maintain a degree of insulation.

The appliance need not have an internal refrigerator engine if cold air is produced elsewhere, for example in a remote fan coil unit, and pumped to the appliance. Thus, the refrigerator engine can be included in the cabinet as an integral unit or cooling can be supplied remotely from a typical supermarket refrigeration pack unit. Local cooling necessitates a drainage system for condensate water.

To deal with any condensation that may form in a ducted shelf, such shelves may be provided with drains to collect moisture and to drain it away. For example, a return duct in a ducted shelf could be inclined downwardly and rearwardly to fall toward the rear of the cabinet, where it may lead water to a drainage system provided for the evaporator to reject water from the cabinet.

If used in the appliance, cooling coils and fans may be located behind the cells but could instead be situated to the top, bottom or sides of the cells. 

1. A ducted shelf assembly comprising: at least one support that is engageable with support formations to hold the shelf assembly at a desired height against a wall of a display appliance; and at least one duct element that is separate from and positionable upon the support, the duct element then being supported by the support.
 2. The assembly of claim 1 further comprising a top shelf component.
 3. The assembly of claim 2, wherein the top shelf component comprises a top plate of the shelf that overlies the, or each, duct element.
 4. The assembly of claim 2 or claim 3, wherein the top shelf component comprises a shelf front strip that is insulated, heated or of low thermal conductivity and is arranged to cover a front edge of the, or each, duct element.
 5. The assembly of any preceding claim and comprising a supply duct element and a return duct element.
 6. The assembly of any preceding claim and comprising separate upper and lower supports, each being separately engageable with support formations to hold the shelf assembly at a desired height against a wall of a display appliance, wherein the duct element is separate from and positionable between the lower support and the upper support, the duct element then being supported by the lower support and retained by the upper support.
 7. The assembly of claim 6, wherein the lower support and the upper support are separately and successively engageable with the support formations upon assembly of the structure against the wall.
 8. The assembly of claim 6 or claim 7, wherein the supply duct element and the return duct element are in layered face-to-face relation and are held together by upper and lower supports.
 9. The assembly of any preceding claims, wherein upper supports positionable above the duct element and/or lower supports positionable below the duct element comprise sealing elements arranged to seal against the wall of the display appliance.
 10. The assembly of claim 9, wherein the, or each, sealing element is arranged to seal against the, or each, duct element.
 11. The assembly of claim 9 or claim 10, wherein the, or each, sealing element has a wall that extends vertically to an extent that enables sealing against the wall of the display appliance to be maintained if a support is engaged with support formations at a different level on the wall.
 12. A ducted-shelf air curtain display unit, comprising at least one ducted shelf assembly of any preceding claim.
 13. The unit of claim 12, comprising an open-fronted cabinet having a display space bounded by an upright wall, that wall being disposed between the display space and at least one riser duct for the supply and/or return of air; wherein: the ducted shelf is selectively locatable in the display space at different heights relative to the upright wall and communicates with the riser duct by engagement of a connector of the shelf via at least one port in the upright wall; the port is deeper vertically than the connector of the shelf such that the shelf can be relocated vertically with the connector remaining in communication with the riser duct via the port after relocation; and a sealing element is relocatable with the shelf to extend between the shelf and the upright wall, the sealing element overlapping an edge of the port to close off a portion of the port not closed by the connector.
 14. The unit of claim 13 and comprising an upper sealing element extending above the shelf to above an upper edge of the port and a lower sealing element extending below the shelf to below a lower edge of the port.
 15. The unit of claim 13 or claim 14 and being arranged such that engagement of a support with the upright wall presses the sealing element against the upright wall.
 16. A method of assembling a ducted shelf in a display appliance, comprising: attaching a first support to an upright wall that bounds a display space of the appliance; and placing at least one duct element onto the first support attached to the wall.
 17. The method of claim 16, further comprising attaching a second support to the upright wall to retain the, or each, duct element on the first support.
 18. The method of claim 16 or claim 17, comprising coupling the duct element to a riser duct of the appliance via a port in the upright wall.
 19. The method of any of claims 16 to 18, comprising stacking supply and return duct elements on the first support before attaching the second support to the upright wall.
 20. The method of any of claims 16 to 19, comprising effecting seals between the first support and the upright wall and between the first support and the or each duct element
 21. The method of claim 20, further comprising effecting seals between the second support and the or each duct element, and between the second support and the upright wall.
 22. The method of claim 20 or claim 21, wherein said seals are effected by assembling together a support and the duct element on the upright wall. 